May 2009

May Meeting Monday, May 4, 7:30 PM, at First Christian Church

Sixth and Osage.

Meeting in the Fellowship Room.

(Please use the East entrance under the awning)

Fred Frey will discuss a series of star trail photos he has taken with a telephoto lens.

There will also be time for informal discussion, so bring anything of interest.

Subsurface Ocean on Enceladus?

Geysers spouting from Saturn's moon Enceladus may originate from a subsurface sea of salty water according to planetary scientists. When NASA's Cassini spacecraft passed through the geyser's plume October 9, 2008, on-board instruments detected sodium in the form of salt and sodium bicarbonate. Since these chemicals must have originated in the rocky core of the moon, liquid water would probably be necessary to leach them from the core and transport them to the plume. A frozen subsurface ocean would likely have concentrated the salt far from the moon's surface, further supporting the idea of a current day subsurface liquid water ocean.

"It's easier to imagine that the salts are present in a liquid ocean below the surface," said Julie Castillo of NASA's Jet Propulsion Laboratory. "That's why this detection, if confirmed, is very important."

<http://www.universetoday.com/2009/04/29/salt-in-enceladus-geysers-hint-at-subsurface-liquid-ocean/>

Recurrent Nova U Scorpii May Blow Up This Year

Since 1900, one of the most famous recurrent novae, U Scorpii, has erupted on average every 10 +/-2 years. The last three occurred in 1979, 1987 and 1999, so another eruption is likely in the coming months. Normally this star, north of Antares, is a very faint 17.6 magnitude. But when it erupts, it brightens in only 5 hours to 8th or 9th magnitude, then declines two magnitudes from the maximum within 38 hours. This makes it the fastest known nova. Monitoring by amateurs throughout the year offers the opportunity to catch the early hours of eruption, which can aid professional astronomers in better characterizing the mechanism driving novae eruptions. The American Association of Variable Star Observers (AAVSO) is actively recruiting amateur astronomers to mobilize a continuous monitoring campaign of U Sco. For more information, check the following links.

<http://www.skyandtelescope.com/observing/highlights/43435242.html>

<http://www.aavso.org/news/usco.shtml>